APPLE has issued a worldwide warning to update iOS security setting on iPhones after hackers developed malware that can break into every iPhone in the world.

According to an article from news.com.au hackers rom NSO Group developed a sophisticated piece of malware that exploited three previously unknown vulnerabilities in Apple's iOS.

Tech site Lifehacker reports that security researchers discovered an unprecedented exploit on iOS that was used by a "digital arms dealer" to spy on political dissidents and high-value targets.

"Investigators found that an Israeli company called NSO Group was able exploit three security vulnerabilities on iOS, enabling users of their software to monitor calls, messages, and more on infected phones,'' the site reported.

Human rights activist Ahmed Mansoor was targeted by someone attempting to infect his phone and forwarded the suspicious text messages he received to researchers at Citizen Lab, as detailed by Vice.

"They then worked with Lookout and Apple's security team to patch the vulnerabilities in an update that is rolling out today (iOS 9.3.5).

"The intended use of the malware is to target high-value individuals and most people aren't really at risk, though it's possible that it's been around as far back as 2013."

After learning of the hack, Apple developed a patch that is now available globally to every iPhone user with its latest iOS update, which it is advising people to down immediately.

"Apple's security advisory on the iOS 9.3.5 update says it addresses threats that could impact parts of the operating system, create memory corruption issues and open users to the possibility of malicious web sites to plant code and take control of their device."

"While the company that identified the exploits noted that they would only have been used against specific high-value targets, the publicity around them means it's more likely that criminal types would add them to their arsenal of attacks, so updating today would be exceptionally wise."

How to update your phone now:

To download the update, go into Settings, then into General.

There should be a Software Update button to click on.

The iOS 9.3.5 update should be available.

The information accompanying the update says it is an important security update for your iPhone or iPad and is recommended for all users.